Contactless synchronizer, particularly for sewing machines

ABSTRACT

Synchronizer without contacts, particularly for sewing machines, utilizes a unitary assembly of rotating position indicators for reducing flux changes in a common field and a transistorized oscillating circuit for converting the flux changes into separate signals for different control functions.

United States Patent Gaa Aug. 8, 1972 [54] CONTACTLESS SYNCHRONIZER,[56] References Cited PARTICULARLY FOR SEWING MACHINES UNITED STATESPATENTS [72] Inventor: Hans Gaa Hockenheim, Germany 3,311,824 3/1967Pitt ..250/233 X 3,128,387 4/1964 Hughes et al. ..340/271 X AssigneerFirm" Frflnkl & Kirchner Fflbrik 2,154,287 4/1939 Schewe ..331/181 xElekmmmmn Elektrische 3,502,955 3/1970 Minks ..331/181 x Apparate,Schweitzingen/Baden, Germany FOREIGN PATENTS OR APPLICATIONS [22] Filed:Feb. 13, 1970 1,047,560 11/1966 Great Britain ..112/219 A 9 [21] Appl NO11,0 9 Primary Examiner-Roy Lake Assistant ExaminerSiegfried H. Grimm[30] Foreign Application Priority Data Am R b H J ob Feb. 18, 1969Germany ..P 19 07 975.5

[57] ABSTRACT [52] CL -331/65v 112/219 A, 250/220 R, Synchronizerwithout contacts, particularly for sewing 250/233, 318/467, 331/66,331/117 R, machines, utilizes a unitary assembly of rotating posi-331/172, 340/271 340/282 tion indicators for reducing flux changes in acommon [51] Int. Cl. ..D05b 69/00, H03b 5/12 field and a transistorizedoscillating circuit for com [58] Field of Search ..112/219 A; 331/65,66,172,

verting the flux changes into separate signals for different controlfunctions.

6 Claims, 5 Drawing Figures PHENTEmus 8 I972 SHEU 2 BF 3 van for ///W544/: WW

75MB VARIAEL'E' PATENTEDAm; 81912 3.683.294 sum 3 or 3 In ven tor:fiA/Vf M BACKGROUND OF THE INVENTION The invention relates to acontactless synchronizer or position setter, especially for sewingmachines. Position setters are intended to initiate certain controloperations such as stopping of the machine, actuation of a thread cutteror of a presser foot on reaching or passing through predeterminedoperating positions of the controlled machine. For this purpose theyinclude position indicators coupled with the moving part of the machine,which in the position for which they are set automatically initiate thedesired control operation. Synchronizers operating with electricalcontactors may include several contact cam disks intended for differentcontrol operations; synchronizers operating without contacts, on theother hand, require sources of rays such as light sources or magneticfield sources, for example permanent magnets or electromagnetic coils,that are provided in the vicinity of the rotating position indicator andwhich therefore must be installed directly in the synchronizing device.In this connection the accommodation and relative separation of separateray or field sources in the device proper causes difficulties andnecessitates an increase in the structural dimenslons.

SUMMARY OF THE INVENTION The invention is intended to eliminate theproblems of the prior art. It is particularly concerned with acontactless synchronizer particularly for sewing machines having severalrotating position indicators for different control operations, and it ischaracterized in that a common field or radiating source is provided forseveral control operations in the range of which at least two positionindicators that act on the field are rotating as a unit.

These position indicators may be perforated shield disks known per sewhich are coupled with the machine that is being surveyed and which,depending on their position, interrupt or release the field or the ray.At the side remote from the source there are located receivers thatrespond to changes of the field or of the radiation, which emitcorresponding impulses to the control devices which cause or initiatethe desired control functions.

For example, a common light source is disposed between at least tworotating slotted shields or a magnetic coil between at least twomagnetic shields which, depending on their position, alternately shieldand open the light source or the magnetic field and thereby effectdifferent control operations. The action of the control means to beinfluenced may, moreover, be the same as in a contact making or contactbreaking action. These control means disposed externally of thesynchronizer are not the subject of the invention and therefore need notbe described in detail.

In lieu of the magnetically intercepting shields it is also possible toprovide rotating magnetic bridges, which as they pass, direct magneticfields into certain paths and thereby initiate the intended controloperatrons.

In all cases the invention makes it possible to utilize one and the samesource of rays or field source for several control operations wherebydifferent sectors of the field of rays or of the magnetic field can beacted on by the position indicators cooperating with the same source.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of a synchronizer orposition setter in accordance with the invention is described in thedrawings, where a magnetic coil is arranged between at least twomagnetic shields. Here this magnetic coil is a component of a feedbackcoupled transistor oscillating circuit, and magnetic shields withpassage areas that are displaced with respect to one another rotate inthe magnetic field of the feedback coil.

FIG. 1 shows the synchronizing device in a longitudinal section,

FIG. 2 shows another section similar to FIG. 1 to an enlarged scale,illustrating particularly the circuit components,

FIG. 3 is a bottom view of the components illustrated in FIG. 2,

FIG. 4 is a circuit diagram of the feedback oscillating transistorcircuit, and

FIG. 5 shows a synchronizer in accordance with FIG.

2 using a ray emitting light source between two rotating slotted disks.

DESCRIPTION OF THE INVENTION In accordance with FIG. 1 the synchronizeris in the form of a structural unit enclosed in a removable housing 1adapted to be coupled to the end of the arm shaft of a sewing machine.It includes a base plate 2 in which a shaft 3 is journalled in the ballbearing 6. This shaft carries at one end a connecting socket 3a that canbe connected to the end of the arm shaft of the sewing machine. Theshaft 3 has secured thereto shield disks 4 and 5 which serve as positionindicators and rotate with the shaft and which are suitably angularlyadjustable.

The stationary part of the synchronizer is supported by a frame 7 thatcan be seated on the base plate 2 and which upon mounting of the circuitcomponents may be filled with a resinous substance. The components areprotected by the resin filling 8 and held in their respective positions.

The synchronizer frame 7 in accordance with FIG. 5 has a common lightsource 9 disposed between the rotating slotted disks 4 and 5. The raysemitted by the light source 9 are bunched in the lenses 12, 13 and arereceived by photocells 10, 11 as determined by the movement of shields4, 5.

The feedback transistor circuit in accordance with FIG. 4 comprisesthree magnet coils L1, L2 and L3, between which project the shield disks4 and 5. These shield disks which are provided with radial slotsconstitute magnetic shields which upon rotation establish and interruptthe passage of magnetic flux therethrough, or which in other wordsinterrupt or open the magnetic fields that extend between the coils L1and L3, respectively L2 and L3, depending on whether the closed portionsof the disks or the slots provided therein are at the time disposedbetween the coils.

The circuit in accordance with FIG. 4 includes, besides the back coupledtransistor T and the coils L1, L2 and L3, five ohmic resistors R2, R3,R36, R37, R39, two adjustable temperature responsive resistors or hotconductors R1 and R38 serving for temperature compensation, as well asthree capacitors C8, C9 and C11. The resistor R36 and the combination ofthe resistors R37, R38 and R39 form together a potential divider at thejuncture point of which the base of the transistor T15 is connected. Theemitter-base potential of the transistor is adjusted by means of thepotential divider to its bias value. The resonance frequency of theoscillating circuit is determined by the inductance and'the capacitanceof the oscillating circuit defined by the coil L3 and the condenser C9.The condenser C8 serves for bridging the high frequency of the resistornetwork R37, R38, R39. This circuit branch contains the resistors R1,R2. The capacitor C11 forms a supplemental feedback coupling. Theoscillator circuit is connected by means of the terminal A3 to thenegative pole and, depending on the control operation to which it isadjusted, either with the terminal Al or A2 by means of a switch sw tothe positive pole of a direct current source B of, for example, 7 volts.In series with the terminal A3 there is connected a resistor R40 of, forexample, 1,000 ohms at which the initial signal is picked up. This isthen fed, if need be upon further amplification, to the control devicesof the sewing machine that are to be operated.

The oscillating circuit operates as follows:

It is assumed that coil L1 is in circuit by way of the terminal A1. Aslong as the closed part of the shielding disk 4 is between the coils L1and L3, there exists no feedback. Depending on the values of theresistors R36, R37, R38 and R39, the transistor T15 carries a smallcollector current determined by the emitter-base potential. If the slotof the shield disk 4 passes between the coils L1 and L3, there developsa rectified altemating current between the emitter and the baseas aresult of the feedback arising between them. As a con-' sequence thebias of the base and thereby the-collector current increases. As aresult the internal resistance of the circuit between the terminals A1and A3 decreases and the initial current increases producing a voltagedrop across the aforementioned 1,000 ohms resistor R40 preceding theterminal A3. This voltage drop can be utilized as the signal-for thepassage of the slot of the shield and for the instant operating positionof the sewing machine in the same manner as with a contact synchronizer.In operation, a small emitter current flows through coil L1 whenterminal A1 is connected to the source of direct current. When the slotof the shield disk 4 appears between coils L1- and L3, the flux fromcoil Ll induces a voltage in coil L3 which causes resonance circuit L3C9 to oscillate, thereby producing an oscillator signal between theemitter and the base of transistor T15. This causes amplifiedoscillations in the emitter-collector circuit, so that the oscillationsrapidly build up due to the positive feedback from coil L1 to coil L3.When the shielding disk 4 again blocks coupling between coils L1 and L3,the circuit stops oscillating. Coils L1 and L2 are, therefore, the fluxproducing means, and coil L3 is the sensing means. However, only one ofthe coils L1 and L2 and the corresponding shielding disks 4 and 5 areoperative at one time, depending on the connection of terminals A1 and'th the d. .s cc. ril same oger ti ons take place when the coil L2 isconnected by way of terminal A2 to the positive pole of the directcurrent source and the shield disk 5 passes with its slot between thecoils L2 and L3.

Having now described the invention, what I desire to protect by LettersPatent of the United States is set forth in the appended claims.

I claim:

1. In a synchronizer having two rotatable position indicators fordifferent control functions, the combination of an rotary shaftsupporting said indicators coaxi ally in laterally spaced and rotatablyadjustable relation to each other, energy flux producing means fixedlypositioned at the axially outer sides, respectively of said positionindicators, said indicators being operable upon rotation thereof tocontrol passage of said energy flux therethrough, sensing means fixedlypositioned intermediate, said indicators and responsive to said passageof said energy flux through said indicators; and an electrical circuitcontrolled by said sensing means to produce signal outputs in responseto rotation of said position indicators, said energy flux producingmeans being magnetic coils and said position indicators being magneticshield disks having radial slots, respectively, for the passage ofmagnetic flux from said coils through said disks to said sensing means.

2. A synchronizer in accordance with claim 1, where said magnetic coilsare components of an oscillator circuit having a feedback field in whichsaid magnetic shield disks rotate.

3. A synchronizer in accordance with claim 2, where said slots aredisplaced relative to one another.

4. Synchronizer in accordance with claim 3, where said oscillatorcircuit includes a transistor.

5. Synchronizer in accordance with claim 4, where said oscillatorcircuit includes a potential divider provided with a first hot conductorconstituting a temperature compensator.

6. Synchronizer in accordance with claim 5, including a capacitivecircuit branch serving as a high frequency bridge for a plurality ofpotential dividers and including a second hot conductor for temperaturecompensation.

' UNITED STATES PATENT OFFICE QETIMCATE OF CORREQHQN Patent No.j,685,294I I Dated AUg'LlSt 8, 1972 Inventor 3) H8118 G88.

' It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Signed and sealed this 19th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,IJR. Attesting Officer ROBERT GOTTSCHALK Commissionerof Patents USCOMM-DC 60376-P69 h us. GOVERNMENT FFHNYING OFFICE: I969o-aes-gsa FORM PO-105O (10-69) UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTIQN Paterit No. Dated Aug-rust 8, 1/72 Inventor( s HElYlS08.8.

It is celftified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Signed and sealed 'this 19th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. Attesting Officer ROBERT GOTISCHALK Commissionerof Patents 7 v USCOMMDC 60376-1 69 U.S. GOVERNMENT PRINTING OFFICE 1I969 O-366-33fl FORM PO-105O (10-69)

1. In a synchronizer having two rotatable position indicators fordifferent control functions, the combination of a rotary shaftsupporting said indicators coaxially in laterally spaced and rotatablyadjustable relation to each other, energy flux producing means fixedlypositioned at the axially outer sides, respectively of said positionindicators, said indicators being operable upon rotation thereof tocontrol passage of said energy flux therethrough, sensing means fixedlypositioned intermediate, said indicators and responsive to said passageof said energy flux through said indicators; and an electrical circuitcontrolled by said sensing means to produce signal outputs in responseto rotation of said position indicators, said energy flux producingmeans being magnetic coils and said position indicators being magneticshield disks having radial slots, respectively, for the passage ofmagnetic flux from said coils through said disks to said sensing means.2. A synchronizer in accordance with claim 1, where said magnetic coilsare components of an oscillator circuit having a feedback field in whichsaid magnetic shield disks rotate.
 3. A synchronizer in accordance withclaim 2, where said slots are displaced relative to one another. 4.Synchronizer in accordance with claim 3, where said oscillator circuitincludes a transistor.
 5. Synchronizer in accordance with claim 4, wheresaid oscillator circuit includes a potential divider provided with afirst hot conductor constituting a temperature compensator. 6.Synchronizer in accordance with claim 5, including a capacitive circuitbranch serving as a high frequency bridge for a plurality of potentialdividers and including a second hot conductor for temperaturecompensation.